Addition Of Blast Furnace Slag Research Articles

Research on the pretreatment and mechanical performance of undisturbed phosphogypsum

In this study, dehydration process of original phosphogypsum (PG) was firstly studied by differential thermal analysis method, and the optimal heat treatment temperature was obtained. Subsequently, the effects of dehydration time and ageing time on compressive and flexural strengths of PG pastes were studied. Additionally, the influence of blast furnace slag, silica fume and Portland cement on compressive strength of PG were determined. Results showed that CaSO4·2H2O in PG were dehydrated at three steps and the related dehydration temperatures were 80 ℃, 140 ℃ and 160 ℃. When the dehydration duration at 140 ℃ was 9 h and the ageing time was 5 d the PG paste obtained the best flexural and compressive strength. The addition of blast furnace slag and cement behaved a positive effect on the mechanical strength of PG. The 28 d compressive strength of PG mixture was increased by 97.8 % when the dosage of cement was 40 % by the mass ratio of total binder. Unfortunately, fly ash led to the decreasing mechanical strengths of PG mixture.

Rheology and Mechanical Properties of Fly Ash-Based Geopolymer Mortars with Ground Granulated Blast Furnace Slag Addition

Geopolymers are less energy-demanding alternatives to Portland cement binders. The subject of geopolymer rheology has not yet been fully explored, and the available literature is limited to a narrow range of material compositions. This paper presents the rheological and mechanical response of fly-ash based geopolymer mortars. Investigations were made of the effect of different levels of ground granulated blast furnace slag (GGBFS) addition levels on the rheological properties of fresh geopolymers as well as their mechanical performances at 2, 14 and 28 days. The aim of the study was to obtain flow curves and to establish the correlation between shear stress and shear rate. The results have shown that geopolymer mortar is a pseudoplastic liquid presenting shear thinning behavior, moreover, with the increase of GGBFS content, higher material strengths were obtained and the total porosity was reduced.

Aplikasi Response Surface Methodology pada Optimasi Penambahan Blast Furnace Slag Terhadap Waktu Pengikatan dan Kuat Tekan Semen

The production of clinker consumes high energy and causes high production cost of cement industry. It can be reduced by adding blast furnace slag as a mixture in cement production. The blast furnace slag - clinker mixture can produce cement with setting time and compressive strength according to SNI. The effect of the addition of blast furnace slag as a clinker mixture to the setting time and compressive strength of cement can be optimized by response surface methodology (RSM) using Central Composite Design (CCD). Optimization by using RSM aims to determine the optimum condition of the blast furnace slag – clinker mixture to the initial setting time, final setting time, and compressive strength. ANOVA test results and response surface analysis show that the addition of blast furnace slag into the cement mixture has a significant influence on the initial setting time, final setting time, and compressive strength. The addition of 5% blast furnace slag with 92.5% clinker in the mixture of clinker and gypsum is the optimum condition which gives a significant effect on the response variable.

Durability and microstructure analysis of the road base material prepared from red mud and flue gas desulfurization fly ash

The present study aimed to investigate the durability and microstructure evolution of road base materials (RBM) prepared from red mud and flue gas desulfurization fly ash. The durability testing showed that the strength of RBM with the blast furnace slag addition of 1wt%, 3wt% and 5wt% reached 3.81, 4.87, and 5.84 MPa after 5 freezing–thawing (F–T) cycles and reached 5.21, 5.75, and 6.98 MPa after 20 weting–drying (W–D) cycles, respectively. The results also indicated that hydration products were continuously formed even during W–D and F–T exposures, resulting in an increase of the strength and durability of RBM. The observed increase of macropores (>1 μm) after F–T and W–D exposures suggested that the mechanism of RBM deterioration is pore enlargement due to cracks that develop inside their matrix. Moreover, the F–T exposure showed a greater negative effect on the durability of RBM compared to the W–D exposure. The leaching tests showed that sodium and heavy metals were solidified below the minimum requirement, which indicates that these wastes are suitable for use as a natural material replacement in road base construction.

Evolution of Mechanical Properties with Time of Fly-Ash-Based Geopolymer Mortars under the Effect of Granulated Ground Blast Furnace Slag Addition

Geopolymers are considered to alternatives to Portland cement, providing an opportunity to exploit aluminosilicate wastes or co-products with promising performances in the construction sector. This research is aimed at investigating the strength of fly-ash-geopolymers of different ages. The effect of granulated blast furnace slag (GGBFS) as a partial replacement of fly ash (FA) on the tensile (ft) and compressive strength (fc), as well as the modulus of elasticity, is investigated. The main advantage of the developed geopolymer mixes containing GGBFS is their ability to set and harden at room temperature with no need for heating to obtain binding properties, reducing the energy consumption of their production processes. This procedure presents a huge advantage over binders requiring heat curing, constituting a significant energy savings and reduction of CO2 emissions. It is found that the development of strength strongly depends on the ratio of fly-ash to granulated blast furnace slag. With the highest amount of GGBFS, the compressive strength of geopolymers made of fly-ash reached 63 MPa after 28 days of curing at ambient temperature. The evolution of compressive strength with time is correlated with the development of ultrasound pulse velocity methods, which are used to evaluate maturity. The modulus of elasticity changes with strength and the relationship obtained for the geopolymer is presented on the basis of typical models used for cement-based materials. The tensile to compressive strength ratios of the tested geopolymers are identified as higher than for cementitious binders, and the ft(fc) relationship is juxtaposed with dependencies known for cement binders, showing that the square root function gives the best fit to the results.

Зарубіжний досвід утворення та використання доменних шлаків

We should regard an issue of efficient use of feedstock and, in particular, a transition to waste-free technology from the perspective of adjusting differences between economic growth (more resources in production required) and “productive capacity” of the environment (depletion of mineral resources, lowering of resources quality, disruption of environment balance). It is possible to adjust these differences not only by using resources rationally and comprehensively but also by processing generated industrial waste. In the Ukrainian metallurgical industry, these issues are very important because of the abundant practice of use of out-of-date resource and energy-intensive technologies and feedstock of poor quality. International experience shows that the metallurgical industry has rich potential in reducing generated waste. On average specific solid waste generation for a unit of product in the metallurgical industry in developed countries is 1.5-3 times lower than in Ukraine. One of the important processes of blast-furnace performance is the generation of slag; slag is one of the most valuable secondary materials. Recently international metallurgical enterprises started implementing a hundred percent recycling of use industrial waste. Moreover, for the past decade there were a lot of efforts made to process slag so to meet strict EU environmental requirements, hence we can regard it not as waste but as an industrial by-product. We use slag mainly in the road sector – for road construction, agriculture ‒ for liming of soils, metal industry – as an iron-containing substance for secondary melting in blast furnaces. The cement industry is the main consumer of blast furnace slag. EU regulations allow up to 35% of granulated blast furnace slag in Portland cement and up to 80% in Portland blast-furnace cement. The addition of blast furnace slag into the mixture increases the performance of blast furnaces and reduces fuel consumption by 15% and prime cost by 25-30 %. Apart from that the slag as an additive considerably improves several construction and technical peculiarities of cement. International experience and expert assessments say that Ukraine has not only huge potential in reducing blast furnace slag generation but also a need for its comprehensive processing with up-to-date technologies and state-of-the-art equipment that can bring an economic and environmental advantage.

Investigation of High Temperature Behaviors of Different Cure Applied Concretes

Concrete is produced cement-bonded system, which is a composite material formed by the combination of different components. The hydration process of the cement and the hydration products affect the mechanical and technological properties of the concrete. In this sense, the curing process is needed to achieve the targeted mechanical properties. In this study, concrete samples were produced by using additives with different origins called mineral additives. The samples were subjected to pressurized steam curing with the help of autoclave at different temperature and pressure values. After the curing process, the compressive strength of the test samples were investigated. In addition, the cured samples were kept in high temperature furnaces at 450 and 900 0C for 6 hours and the compressive strength of the samples were examined. As a result of the study, it was found that the autoclave cure caused an increase in the compressive strength of the concrete at 400 0C. The best high temperature resistance values were determined in the blast furnace slag addition series.

Anhydrite, blast-furnace slag and silica fume composites: properties and reaction products

Mixtures of a composite binder based on anhydrite synthesised from waste plaster from the ceramics industry complemented with granulated blast-furnace slag (BFS) and silica fume (SF) were studied. Small additions of potassium sulfate, calcium hydroxide and Portland cement clinker were used as chemical activators. The addition of BFS and SF to the systems was found to improve the properties and hinder the dissolution of gypsum in wet environments. The presence of ettringite was visually verified by scanning electron microscopy. The samples did not show considerable expansion or loss of mechanical properties for up to 56 d. The strength obtained by the compounds after 56 d was ∼20 MPa, far exceeding the typical compressive strength of gypsum plaster (about 4 MPa). The main hydrated products were gypsum, ettringite and calcium silicate hydrate type products.

Hydrogen production of bio-oil steam reforming combining heat recovery of blast furnace slag: Thermodynamic analysis

Hydrogen production via steam reforming of bio-oil combining heat recovery of blast furnace slag was investigated via thermodynamic analysis in this paper. The addition of blast furnace slag just had a slight enhancement for hydrogen production from the steam reforming process of bio-oil at low temperature, and had almost no thermodynamic effect (either promotion or restraint) for the steam reforming reaction equilibrium at high temperature where higher H2 yield were obtained, no matter how much blast furnace slag was added. However, different masses of blast furnace slag as heat carrier supply different amounts of heat, so the optimal blast furnace slag addition was performed via energy balance. If the sensible heats of the reformed gas and the slag after steam reforming reactions were unrecycled, the required mass of blast furnace slag was over 30 times of bio-oil mass, while the required slag mass was just 11.5 times of bio-oil mass if the sensible heats after the steam reforming reactions were recycled. For the latter, about 0.144 Nm3 H2 per kg blast furnace slag was obtained at the reforming temperature of 700–750 °C and the steam/carbon mole ratio of 6.

Application of Metakaolin-slag Binders to Solidify Rad-waste Glass Sharps: Leaching of 137Cs and 152+154Eu Radionuclides

METAKAOLIN (MK) and blast furnace slag (BFS) were utilized to design alkali activated binders suitable for solidification of waste glass (WG sharps contaminated with 137Cs and 152+154Eu radionuclides). Two forms of WG, powdered and fused, were utilized. Effects of WG forms and BFS addition on the ability of formulations to withstand compression were preliminary studied. When cold powdered WG was solidified the corresponding compressive strength (MPa) values were decreased by increasing the loading percentages. While fused forms were positively affected MPa values till 10.0% loading. Positive relations between BFS addition and MPa values were also detected. Leaching of 137Cs and 152+154Eu from MK-based formulations was followed as affected by WG forms, BFS addition and early age (2hr) curing temperatures. Both studied radionuclides were cumulatively leached in larger fractions from solidified powdered WG than from fused one. The obtained results reflected the ability of the designed formulations to retain 137Cs in greater extents than 152+154Eu. The lowest diffusion coefficient values (2.01×10-11 and 3.92×10-10cm2/s) were recorded when fused forms of WG containing 137Cs and 152+154Eu, respectively, were solidified into slag seeded MK-based formulations, early aged cured at 40°C. Slope values of log(CLF) vs. log(time) plots were < 0.35 indicating that the controlling leaching mechanisms for all studied leaching systems were predicted to be wash-off.

Effect of retarders on flow and strength development of alkali-activated fly ash/blast furnace slag composite

Abstract Geopolymer concrete presents a major problem regarding its practical application, in that the geopolymer paste has very short setting time. Previous studies have shown that the addition of blast furnace slag to geopolymer paste considerably shortens the setting time. Based on these findings, in the present study, setting retarders were used to lengthen the setting time of the geopolymer paste. The objective of the present study was to identify the effect of a setting retarder on the fluidity and compressive strength of alkali-activated fly ash/blast furnace slag-based materials. It was shown that, by adding a chelator as a retarder, the setting time can be prolonged. However, the setting time was found to be dependent on the type of chelator. Similarly, the compressive strength development of the geopolymer was also found to be dependent on the type of chelator. It was clarified that the concentration of calcium and aluminum in solution during hardening changes with the addition of a chelator, and it was shown that there is a correlation between the concentrations of calcium and aluminum and the setting time.

Effect of ferronickel slag as fine aggregate on properties of concrete

This study investigated the influence of ferronickel slag replacing sand as fine aggregate on the properties of concrete under the same superplasticizer content. The results indicate that the addition of two types of ferronickel slag decrease the workability of fresh concrete. The addition of blast furnace slag (BS) obviously decreases the apparent density of concrete while the addition of electric furnace slag (ES) slightly increases the apparent density. Mechanical strengths increase with BS content increasing, but decrease with ES content increasing. High BS content can improve the resistance of concrete to chloride ion penetration while using ES as fine aggregate has little effect on the resistance to chloride ion penetration. Water absorption of concrete decreases with BS content increasing but increases with ES content increasing. BS has a positive impact on sulfate attack resistance and fire resistance. Using 25% ES also has an active effect on resisting sulfate attack. However, the addition of ES has little effect on improving the fire resistance of concrete. As a result, using 75% BS or 25% ES is the best choices in engineering application.

Effects of sulfate and magnesium ion on the chloride transportation behavior and binding capacity of Portland cement mortar

The chloride diffusion induced reinforcement corrosion seriously threatens the durability of concrete construction in marine environments. This paper investigates the effects of sulfate and magnesium ion in simulated seawater on the chloride transportation behavior and binding capacity of Portland cement mortar with and without fly ash (FA) and ground blast furnace slag (BFS). Chloride ion transport profile, binding capacity and corrosion products of mortar specimens exposed to NaCl, NaCl + MgCl2, NaCl + Na2SO4 and NaCl + MgCl2 + Na2SO4 solutions at different penetration depths were conducted respectively. Results indicate that the samples exposed to NaCl + MgCl2 solutions show the highest chloride content at the outmost layer (0–5 mm). The presence of magnesium ion and combined sulfate and magnesium ion in chloride salt accelerates chloride ingress and increase apparent chloride diffusion coefficient, while reduces the content of calcium hydroxide thus results in a reduction of the chloride binding. However, the sulfate ion in NaCl + Na2SO4 solutions inhibits the chloride diffusion, enhances bound chloride and refined the pore size due to the formation of Friedel’s salt (Fs) with chloride ion. Furthermore, the addition of BFS significantly improves the resistance to chloride ingress into mortar specimens.

The Use of Fine Blast Furnace Slag in Improvement of Properties of Concrete

Concrete properties can be improved using Fine Blast Furnace Slag (BFS). The latter was used to replace cement in concrete at 10%, 15%, 20%, 25%, and 30% proportions and properties of both fresh and hardened concrete improved. Best workability (evaluated by slump and Table tests) was recorded at 30% of BFS addition. VEBE-time, an indication of workability of concrete, decreased to its lowest value (about 4 seconds at 30% BFS) and compaction factor attained its maximum value of 99% at BFS 25%. For density and unit weight, 30% of fine BFS in concrete mix resulted in maximum density of 2180 kg/m3 for fresh concrete, and 2430 kg/m3 for hardened concrete. Unit weight of concrete achieved a maximum of 23.9 kN/m3 at 30% BFS has achieved specified strength at 1st week and 28 days, also the late strength is high at 56 and 84 days. Bond and flexure loads come high of BFS use. The data of compressive, bond, and flexural strengths are highly related. Results of research are useful and may be applied using fine BFS to improve the properties of concrete materials.

Simultaneous effect of silica fume, metakaolin and ground granulated blast-furnace slag on the hydration of multicomponent cementitious binders

Portland cement was partially replaced by metakaolin (MK), silica fume (SF) and ground granulated blast-furnace slag (BFS). Globally, two amounts of SF (5 and 10 mass%) and total substitution level of 35 mass% were used to prepare blended samples. Their early and 28 days hydration was studied by means of isothermal calorimetry and thermal analysis. Developed phase composition was assessed using compressive strength measurements. Acceleration of cement hydration in early times was proved and reflected higher amounts of finer additives. Despite dilution effect, the presence of more reactive SF and MK resulted in pozzolanic reactions manifesting already before 2 days of curing and contributing to the formation of strength possessing phases. The influence of BFS addition showed later and thanks to the synergic effect of all the used additives; it was possible to increase its content up to 25 mass% by keeping the compressive strength values near that of referential one.

Blast Furnace Slag Addition Effects on Delayed Ettringite Formation in Heat-cured Mortars

Reducing expansion due to Delayed Ettringite Formation (DEF) is becoming an important issue that must be taken into account, when producing heat-cured concrete. Mineral additives used as partial cement replacement should help in achieving the desired aspect. Based on an ongoing experimental program, this research emphasizes on the effect of Blast Furnace Slag (BFS) on the expansion of cement mortars caused by DEF. For this purpose, mortar prisms in which Portland cement was replaced by BFS, with three different replacement levels (10,20 and 40%) and two finenesses degree (400 and 500 m2/kg) were tested in length change, dynamic elasticity modulus and compressive strength over more than 750 days. Results showed that the efficiency of blast furnace slag in controlling expansion related to DEF was conditioned by its levels of replacement.

Frost resistance of concretes containing ground granulated blast-furnace slag

The paper deals with the influence of addition of ground granulated blast-furnace slag (GGBS) on the frost resistance of concrete. GGBS is a valuable modifier of concrete, having the latent hydraulic properties and particularly improving the chemical resistance of concrete. However, the performance of concretes with blast-furnace slag under freezing and thawing action is still not explained fully and remains a subject to discussion. The authors have investigated the concretes containing various amounts of GGBS and the portland cement CEM I, with various values of water to binder ratio, with and without the use of air-entraining admixture. The results of research show that the addition of blast-furnace slag causes some worsening of the frost resistance of concrete. The extent of this worsening depends on the water to binder ratio and the aeration of the concrete. However, even under the least favourable conditions, the concretes with GGBS addition have met the requirements of frost resistance after 200 cycles of freezing and thawing, given in the Standard PN-B-06265.

Optimizing the Acid Resistance of Concrete with Granulated Blast-Furnace Slag

Concrete for agricultural or industrial applications is often subject to intense acid attack. Most affected structures are sewage structures and biogas plants, natural draught cooling towers or silage silos. Widely independent from acid type, in most cases the acid attack on concrete runs the same way, starting with dissolution of easily soluble calcareous phases like calcium hydroxide. With ongoing attack, calcium-silicate-hydrate crystals (CSH) are also affected by acidic media. In contrast, siliceous phases like silicon-dioxide (SiO2) are widely unaffected by acid attack. While the dissolution of the matrix is increasing with ongoing attack, quarzitic aggregates remain unchanged. Beside the use of coarse SiO2-aggregates, the resistance against acid attack is mainly increased by a minimization of the porosity. For this purpose on one hand, a low water/cement-ratio has to be sought, on the other hand also the fines should be distributed with an optimized grading curve (e.g. Fuller-principle). In practice, this results in a combination of various fine and ultra-fine components, e.g. fly ash, GGBS, silica fume or metakaolin. Such binder compositions lead to a particularly dense microstructure, especially at pore sizes below 1 micron, and a higher chemical resistance due to a lower Ca(OH)2 content. This paper gives an overview on typical acid-resistant concretes, most common applications as well as the effects of the related acid attack and points out the potential of granulated blast furnace slag addition to such concretes.

Mixture design and early age investigations of more sustainable UHPC

This paper deals with the possibility to make the Ultra-High Performance Concrete (UHPC) as an environmentally friendly, through cement replacement with Blast Furnace Slag (BFS) and considering its cost and its early age performance. Thereby, a preliminary investigation is carried out, to design an UHPC with local materials and where Silica Fume (SF) is partially replaced with crushed quartz. The results showed that, from a mixture standpoint: i) the use of high energy mixer is necessary to ensure a homogeneous and workable mixture; ii) the polycarboxylate superplasticizer with chemical structure of acrylic polymer (ACP1) and saturation dosage of 1.8% gives better workability for UHPC, compared to other six superplasticizers; iii) despite its negative effect on slump flow, Grey Silica Fume (silicium) ensures better compressive strength at early age, than Light one (zirconium). Results showed also that for 30% of cement replacement, the nucleation effect of BFS particles prevails and induces an acceleration of setting and hydration reaction of cement. For BFS contents of 50 and 80%, the dilution effect is dominating, which decelerates the setting and hydration reaction and decreases the peak of heat flow. BFS addition also affects the strength development. At 3 days, the strengths of the blended mixtures of UHPC with 50 and 80% of BFS were decreased by 26 and 66% respectively, while in contrast, there was a slight increase in the strength (+3%) with 30% of BFS compared to the reference mixture (UHPC1). For UHPC containing 80% of BFS, the use of chemical activator of potassium hydroxide, with a concentration of [KOH]3, causes slag’s dissolution and reaction, which in turn improves the compressive strength by 42% and 11%, at 3 and 7 days, respectively.

ON THE USE OF SLAG CEMENT COMPOSITIONS IN THE CONSTRUCTION OF WELLS

In the article studies of oil-filled compositions with the addition of blast-furnace slag for strength at elevated temperatures are presented. The rheological parameters of the slag cement slag cement mortar, as well as the setting time, were studied. Conclusions are drawn about the prospects of further study of slag cementcontaining compositions.